About this symptom
A red eye happens when the small blood vessels on the white of the eye swell. Common triggers are dryness, strong sun, dust, allergies, infection and injury.
Most red eyes are minor and clear by themselves. But redness can also come from conditions that can harm sight if they are not treated quickly, so the other signs matter more than the redness itself. Pain, a change in vision, and light hurting the eye are the signs that something more serious may be happening.
Possible causes
This is not a diagnosis. These are the causes doctors think about, with the ones that are most urgent to rule out first.
- GlaucomaA sudden rise in pressure inside the eye (acute glaucoma): a very painful red eye, blurred vision, rainbow rings around lights, headache, nausea and vomiting. A medical emergency.Read about it
- Eye injury or something in the eyeFollows a blow, a scratch, grit, glass or a chemical splash. Pain, watering and a feeling of something in the eye. A cut, a pierced eye or any chemical needs emergency care.
- Corneal ulcerAn infection of the clear front of the eye, including infection linked to contact lenses. Pain, redness, blurred vision and sensitivity to light.
- UveitisInflammation inside the eye. Pain that may be worse when reading, redness, watering, light sensitivity and changes in vision.
- ConjunctivitisRed, gritty or burning eyes, often itchy or watery, with sticky discharge. Usually both eyes, and a change in sight or pain is not typical. Infective forms spread; allergic forms do not.Read about it
- Dry eyeSore, watery or blurry eyes, with redness.Read about it
- Burst blood vessel in the eyeA bright red patch on the white of the eye, often after coughing or straining. No pain and normal sight, and it fades in one to two weeks. More common with blood thinners.
- BlepharitisItchy, sore, crusted edges of the eyelids, with red eyes.
When to get help
Also get emergency care for:
- A very dark red eye, or one pupil bigger than the other
- Rings (halos) around lights, with nausea or vomiting
- Any chemical in the eye, or something stuck in it such as glass or grit
- Severe pain or loss of vision within 4 weeks of eye surgery or treatment
See an eye doctor soon if you have:
- A red eye if you wear contact lenses (see an eye doctor the same day)
- Redness that has not cleared after a couple of days
- Sticky, yellow or green discharge from the eye
- A red or sticky eye in a baby or young child (a newborn needs urgent care)
- Redness in the eye if you take blood thinners
- Itchy, sore, crusted eyelids, or eyelash problems, that last more than a few days
A red eye with no pain, normal sight and no injury is usually minor and can be watched for a few days.
What you can do at home
With any emergency sign, do not stay at home: go for eye care straight away. For a chemical splash, start rinsing first.
Do
- For a chemical splash, rinse with cool running water for 15 minutes, with the eye tilted down and to the side, then get emergency care
- Stop wearing contact lenses while the eye is red
- Wash your hands before and after touching near the eye
- For a mild, painless, sticky red eye, clean the lids with cooled boiled water on cotton wool
Do not
- Do not rub or press the eye
- Do not try to remove something stuck in the eye
- Do not put drops or home remedies in a painful red eye before an eye doctor has seen it
- Do not drive yourself to hospital
- Do not share towels or pillows
What the doctor will do
The doctor will ask whether one or both eyes are red, how suddenly it began, whether it hurts, whether your sight has changed, whether you wear contact lenses, and whether you have had an injury, headache or nausea. They will examine your eye and check your vision.
They may rinse the eye with saline, remove a foreign body, and prescribe eye drops. If the cause is not clear, you may be sent to an eye specialist (ophthalmologist) for more tests. Treatment depends on the cause.
Myths and facts
Things people often say about this. Open each one to see what is true.
Myth“Every red eye is eye flu and will clear by itself.”What is true?
Fact
Conjunctivitis is a common cause, but a red eye can also come from conditions that threaten sight. A red eye with pain, a change in vision, light hurting the eye, an injury or a chemical splash needs urgent eye care.
Myth“You catch eye flu just by looking at someone who has it.”What is true?
Fact
Infective conjunctivitis spreads through contact with the discharge, for example on hands, towels and pillowcases. Washing hands often and not sharing towels or pillows lowers the risk.
Myth“You can keep wearing your contact lenses and the red eye will settle.”What is true?
Fact
Stop wearing contact lenses while the eye is red. If you wear lenses and have a red eye, get urgent advice from an eye doctor, because it could be an eye infection.
Questions to ask your doctor
Tick the ones you want answered and take them with you.
Common questions
How can I tell conjunctivitis from something serious?
Conjunctivitis usually affects both eyes, makes them gritty, itchy or watery with sticky discharge, and does not change your sight. Eye pain, light hurting the eye, blurred vision, or a very red eye can mean something more serious, so get urgent help.
Is a red eye contagious?
Infective conjunctivitis is, and it spreads by contact. Allergic conjunctivitis is not. Many other causes of a red eye, such as dry eye or a burst blood vessel, are not contagious.
A bright red patch has appeared on the white of my eye. Is it dangerous?
A burst blood vessel looks alarming but is usually painless, does not affect sight and fades in one to two weeks. It is more common if you take blood thinners. See a doctor if it hurts, your vision changes, or it follows an injury.
What should I do if something splashes into my eye?
Rinse the eye at once with cool running water for 15 minutes, with the eye tilted down and to the side. Take out contact lenses afterwards if they did not wash out. Then get emergency eye care, because any chemical in the eye needs to be seen.
